Automatic stop mechanism



Aug. 3o, 1932.

D. s. nessi-:

AUTOMATIC STOP IECBNISI- Filed 'ocu 1e. 1929 2 sneets-snet 1 A'n'oRNEY' A'ug. 3o, 1932.

n. ane-.Ese

AUTOIATIC STOPIECHANISI Filed oct. 1s. 1929 -2 Sheets-Sheet 2 Patented Aug. 3o, 1932 nutren srarss PATENT' OFFECE BATTERY COMPANY,

or MADISON, WISCONSIN, A CORPORATION F WISCONSIN AUTOMATIC STOP MECHANISM v Application filed October 16, 1929. Serial No. l00,05'7.

This invention relates to control devices 'for power operated automatic machinery, more particularly to that type of machinery to which power is transmitted from a prime mover or other source by means of a clutch.

It `is also applicable, however, to machines to which power is supplied by direct drive from a prime mover. In the operation of such machinery, circumstances occasionally arise where continued operation will result in damage or excessive wear to the machine, or, at least, a waste of power. It is desirable at such times that the machine be stopped as quickly as possible and my invention provides means for automatically stopping al power operated machine upon the occurrence osuch predetermined conditions. The invention is illustrated in connection with an ordinary power driven press for stamping and shaping articles out of sheet metal but it is not limited to that class of machinery but may be used upon any mechanism where similar problems occur.

In the ordinary operation of a power press, it occasionally occurs, as will be explained hereinafter, that punched stock accumulates in the dies. The continued operation of the punch under such circumstances results in excessive wear upon the cutting surfaces and considerable damage may be done to the dies. Lt the press is driven from a line shaft by a powerful prime mover, failure of the press may occur. if it is individually driven by a motor, the latter may become stalled and burn out.

Upon exhaustion-of the unpunched stock which is being fed to the press, further operation causes a useless consumption of power and results in unnecessary wear upon the cutting edges of the dies.

lt is the general object of this invention to provide, in a power operated machine, means for automatically stopping the machine upon the occurrence of conditions such that further operation will result in damage or useless wear to the machine or if, for any other lreasoncontinued operation is not desired.

More speciiically, it is the objectV of this invention to provide an automatic stop mechanism for a power press which will operate upon accumulation of punched stock in the dies and upon exhaustion of the unpunched stock being fed to it.

Very briefly, the general principle upon which my invention operates is as follows. Accumulation of stock between l the dies causes speed decrease of the press. A device is provided which is responsive to such speed decrease, and further mechanismis provided which operates to disengage the clutch betweenl the press and its source of power selectively upon operation ofthe speed responsive device or upon exhaustion of unpunched stock.

rl`he clutch disengaging mechanism comprises an electro-magnetically operated solenoid with its armature arranged to cause actuation of the clutch disengaging lever upon energizationof the solenoid` The solenoid is connected in series with a source of electrical energy but between the two there are two normally open, parallel connected switches. Closure of either switch closes the circuit between the energy source and the solenoid. One switch is adapted to be closed upon-operation of the speed responsive device and the other upon exhaustion ot unpunched stock. y

Due to thei'amiliarity of those engaged in engineering and mechanical arts with the ordinary power press, only so anueh reference thereto as is necessary for a clear understand-A ing of my invention, will be made in the following description and drawings wherein,

Fig. l, is a general view of an ordinary double action cam press, equipped with the automatic stop mechanism which is the subject of my invention,

Fig. 2 is a detail view of a portion of the circuit controlling means actuated by the eX- lhaustion of stock.

Fig. 3 is a similar. view of the solenoid armature and clutch lever.

Fig. 4 is a detail view of the mechanism.

Fig. 5 is a Jrontview of the power press clutch mechanism, parts being shown in section, Fig. 6 is a side view of the clutch mechanism shown in Fig. 5. 10(

punch and die Fig. 7 is a detailed diagrammatic view of my invention, and

l Fig. 8 is a diagrammatic view of the solenoid energizing circuit. v f

Like numbers designate' like parts in the several drawings. Referring to Fig. 1, the unpunched sheet metal is supplied in rolls 1 which are support- .ed upon a suitable supporting device from .which the strip 2 is unrolled and fed automatically to the die 3. The strip 2 remains stationary during the stamping operation and advances the required distance between such operations. The strip feeding means may be of any conventional type and is, therefore, not disclosed. The stationary die 3 cooperates with reciproca-ting blank-ing punch 4 which stamps out ,a blank from strip 2. Blanking punch 4 is supported in slide 5, to which vertical reciprocal motion is transmitted by means of rollers 6, which in turn, are actuated by cams 7'. Cams 7 are rigidly mounted upon crank shaft 8. Slide V 5 and. blanking punch 4 have central vertical openings within which drawing punch9 (see Fig.

4) reciprocates vertically .and independently of slide 5 and punch 4, motion being transmitted to drawing punch 9 by means of crank" 410 which is also drlven by crank shaft 8.

The blanking punch 4 moves slightly in advance of the drawing punch 9 in the conventional manner. Blanking punch 4 shears a blank from strip 2 and then stops its downward movement at. such a point that it holds the blank upon shoulder 11 of die 3. Drawing punch 9 descends and draws the blank between itself and the constrictedportion of die 3, this space lbeing equal tothe thickness of the sheet metal. The blank assumes a shallow cup shape. Suitable mechanism, not

shown, is provided for stripping the shaped.

blank from drawing punch 9 during its upward movement.

It occasionally happens that drawing punch 9 shears through the blank, leaving a collar or annular ring of metal uponshoulder 11, part of which may extend downward into the constricted portion of die 3. Upon its' next downward movement, blanking punch 4 encounters two thicknesses ofA metal upon.

shoulder 11 with the result that blanking punch 4 can reach the end of its stroke only y crushin the double thickness of metal into a sing e thickness. Drawing punch 9,

' likewise, finds a double thickness of metal between it and the walls of die 3 with the result that great resistance is oifered to its motion. The increased resistance causes speed decrease of the press. If thejpress is not stopped immediately, the sheet metal continues to accumulate in the die and-is chewed into a tangled mass. The shearing surfaces of the disc and punches become worn and damaged and failure of the press is possible.

The ywheel 12 is drivenby a belt 13 which,

20 and slot 17 are engaged when the in turn, is driven by a suitable source of pow# not shown, such as a llne shaft or a motor..

er The flywheel 12 revolves freely upon shaft 8 which may be integral with crank shaft 8. The speed responsive device, which is represented by an ordinary fly ball engine governor, is driven by belt `14 which, in turn, is driven by the hub portion 15 of flywheel 12.

In order that the operation ofthe invention may be more readily understood, a detailed clutch. The driven clutch section 18 isupro.-l

vided with a transverse slot 19 in which a key 20 is adapted to slide.. This key is constantly urged toward the slot 17 in the hub-plate 16 by a spring 21. As shown in Fig. 5, ke

clutc is in its normally engaged position. A rod 22 is connected, by means of link 23, to a wedge 24. Wedge 24 isfurgcd upwardly into contact with clutch section 18 by'a spring 25.

' As this clutch section revolves wedge 24 enters cut-out 26 in key 20 and the key iscaused to slide back against. the tension offspring 21.

The key is thus withdrawn from the 'slot 17 in hub-plate 16 and the clutch sections are disengaged. Friction brake 27 is in constan-t engagement' with driven clutch section 18 and is adjusted to stop the press in slightly less than a single revolution. Rod 22 is connected at its lowerv end to clutch lever 28,

(see Fig. 1). lTo effect engagement ofthe clutch sections, lever 28 is pulled down to disengage wedge 24 from key 20. The `flyy I wheel continues to revolve and, upon engagement of key 20 with slot 17 in hub-plate 16, clutch section 18 will revolve. 28 may be held in its lower position by engaging it beneath latch 29 see Figs. 3 and 7) which may be any projection from the framework of the press. This is the normal operating position of the clutch lever.

My automatic stop arrangement, as shown in Fig. comprises an arm 30, pivoted at 31 and connected at one end to armature 32 of solenoid 33. The oppositeend of arm- 30 contacts with the side of clutch lever 28.

Energization of the solenoid operates the armature 32 to the left on Fig. 7, in which event the arm 30 is adapted to disengage clutch lever 28 from beneath latch 29.

Thereupon spring 25, Fig..5, forces wedge 24 into cut-out 26 to disengage the clutch sections as heretofore described.

The solenoid energization circuit comprises a suitable source of electric energy as indicated at 34, which is illustratedA as being an Clutch lever 1 1 V sure of switch 40.

ordinary two wire circuit. One wire 35 of the circuit is connected directly to one end of the solenoid 33, (see Figs. 7 and 8). The other wire 36 is solidly connected to contacts 37 and 38 of switches 39 and 40 respectively. The cooperating contacts 41 and 42 of switches 39 and 40 respectively are connected to the other end of solenoid 33 by wire 43. As illustrated in Fig. 8, the switches 39 and 40 are connected in parallel electrical arrangement while each is in series connection between the source of energy 34 and the solenoid 33. Closure of either switch 39 or 40 completes the circuit between the source of energy 34, and the solenoid 33 and causes energizat-ion of the latter.

An important feature of the invention isthe manner of securing selective closure of switches 39 and 40 upon the occurrence of predetermined conditions, namely, speed decrease ofthe press and exhaustion of unpiuiched stock. To accomplish the former, a speed responsive device, which may. be an ordinaryV fly-ball enginev governor as illustrated, or any other suitable speed responsive device, is arrangedto close switch 39 upon'.

predetermined speed decrease of the press.

In the construction illustrated in Figs. l and 7, belt 14 drives pulley 44 and the motion is transmitted, by means of bevel gears 45 to arm balls 46. At normal operating speed the balls 46 are raised to the position shown in solid lines in Fig. 7. In such position arms 47 depress` spindle 48 against the supporting action of lever 49, due to the counter weight 50. In the normal operating position ber cam 51, is below the contact 37 of switch 39 as shown in Fig. 7 Any speed decrease of the press causes arm balls portlonate distance with /a corresponding rise of spindle 48 and ber cam 51. With proper care, an adjustment may be made whereby failure of one disc of punched stock to beremoved from Athe punching dies will cause ber cam 51 to be raised from the lower position to the higher position, in which position s witch contact 37 is moved into closed relation withvcontact 41 as shown in Fig. 1.

The mechanism for closing switch 4() upon exhaustion of unpunched stock is as follows. A pivoted arm 52 rests upon strip -2 of unpunched stock as it is fed to the die. This arm .is connected to a spindle 52. The spindle is guide-fl against lateral movement by suitable guideways in switch box 53 mounted on the frame of the press. Fibre cam 54 is arranged on the spindle, and in normal operating position, it is above contact 42 of switch 40 as shown in solid lines in Fig. 7. Upon exhastion"of the strip 2, spindle 5 2 drops to its lower position where it rests upon the bottom of switch box 53. During its descent, cam 54 ca ses momentary cl o v Closure of either of switches 39l or 40 causes 46 to drop a proclutch in the energization of solenoid 33 with resulting` disengagement of the heretofore described.

press clutch sections as Where the press or other machine is driven directly by a motor or steam engine or othervw prime mover without the use of a clutch, the electromagnetic solenoid may be adapted, upon occurrence of predetermined conditions, to open the electric power supply switch of the motor, or shut oif the steam supply to the engine, or shut oii the power supply of such other type of prime mover as may be employed.

While I have described my invention by the aid of a single example and in connection ing means, said interrupting means comprislng a speed responsive device operable upon predetermined speed decrease of said blanking and drawing means to interrupt the pow- 95 er supply ofsaid blanking and drawing means.V

2. In a punch press, the combination with means for blanking and drawing shapes from sheetgpniaterialfof means responsive to 10o undesired c'cumulation ofsaid material in the blanking and drawing npeans for interrupting the operation of the bla-nkig and drawing means, said interrupting means comprising a device responsive to speed decrease of said blanking and drawing means to disengage'a clutch in the power supplyv systeml of said' blanking and drawing means.

3. In a puncldpress, the combination with 110 means for bla ing and" drawing shapes from sheet material, of means responsive to undesired accumulation of said material, in the blanlring and drawing means for interrupting the operation of the blanking and 1115v drawing means, said interrupting means comprising a iy ball engine governor responsive to` predetermined speed decrease of said blanking and drawing means to disengage a blanking and drawing means.

4. In a punch press, the combination with means` for blanking and drawing shapes from sheet material, of means responsive to undesired accumulation of said material in 125 power input system of said blanking and" press, the combination with predetermined power supply system of said drawing means,` electromagnetic means' adapted upon energization to disengage said -rom'sheet material, of means responsive to undesired accumulation of'said material in the blanking and drawing means for inter- A, rupting Jthe operation of the blanking and drawing means,- said interrupting means comprisng, in combination, a clutch in the power input system of said blanking and drawing means, an electromagnetic solenoid adapted, upon energization, to disengage said clutch, an energizing circuit in series with said solenoid, a normally open switch in said energizing circuit, and means responsive to speed decrease of said blanking and drawing means to close said switch.

6. In a power driven punch press, an automatic clutch disengaging mechanism comprising, in combination, a clutch in the power input system of said press, an electromagneti cally operated solenoid mounted upon said press and adapted, upon energization, to disengage said clutch, an energizing circuit in series with said solenoid, two normally open, parallel connected switches in said energizing circuit,

means responsive to predetermined speed variation of said press to close one of said switches, and means responsive to vexhaustion of unpunched stock to close the other of said switches.

7 In a power driven punch press, an automatic clutch disengaging. mechanism comprising, in combination, a clutch in the power input system of said press, anelectromagneti- :ally operated solenoid mounted upon said press and adapted, upon energization, to disengagel said clutch; an energizing circuit in series with said solenoid, two normally open, parallel connectedswitches in said energizing circuit, a fly ball engine governorresponsive to predetermined speed decrease of said press to close one of said switches, and a member, normally supported bythe strip of unpunched 'stock being fed tov said press, adaptedto close the other of said switches upon exhaustion of said unpunched stock.

8. In a power driven punch press for blanking shapes from sheet metal, an automatic stop mechanism comprising, in combination, driving and driven clutch sections in the power input system of said press, one being engageable and disengageable relatively to the other, means to engage and disengage said clutch sections, an electromagneticsolenoid adapted, upon energization, to actuate said clutch operating means to disengage said clutch sections, Aa normally deenergized electrical circuit in series with said solenoid, and separate means operable reblanking shapes spectively upon speed decrease of said punch press and upon exhaustion of said unpunched stock to energize4 said circuit.

9. In a power driven punch press for ing driving and driven clutch sections in the power input system thereof, one being engageable and disengageable relatively to the other, an automatic clutch disengaging mechanism comprising,

engage and disengage said clutch sections,

-disengage said clutch sections,anl energizing circuit in series with said solenoid, two normally open, parallel connected switches in said energizing circuit, means responsive to speed decrease of said punch press toclose one of said switches, and means responsive to exhaustion of unpunched stock to close the other of said switches.`

In testimony whereof I aix my signature.

DAVID B: REESE.

from the sheet metal hav# in combination, means comprising a clutch lever adapted to. 

